High Quality Content by WIKIPEDIA articles! The (Eastern) Black Swallowtail (Papilio polyxenes) also called the American Swallowtail or Parsnip Swallowtail, is a butterfly found throughout much of North America. It is the state butterfly of Oklahoma. There is an extremely similar-appearing species, Papilio joanae that occurs in the Ozark Mountains region, but it appears to be closely related to Papilio machaon, rather than polyxenes.